Array Microscope Assay for Cancer Cell Mechanics Abstract As cells become cancerous, characteristic changes take place in their behavior that affect cell division as well as the ability of the cell to migrate or metastasize. Metastatic behavior, including cell migration, motility and adhesion, is one of the most damaging hallmarks of cancer. Current assays of cell metastases involve the observation of the lateral mobility of cells in a scratch assay, or the translation of cells through porous membranes. These assays usually take several hours to days of cell tracking. Metastatic potential has recently been associated with protrusive ability and cell body mechanical properties. We propose to replace the migration assay with one that measures the cell stiffness and cell mechanical response. This involves performing a calibrated tug on the cell with the measurement of the probe displacement. This measurement takes only seconds. This would allow the replacement of a five to forty eight hour assay with a one minute assay. More important than the simple benefit of a faster measurement on a single specimen, we propose an assay system that will allow high throughput methodologies to be applied to elucidating the time course of the biochemical pathways at the heart of the mechanical, and hence, metastatic propensity. We currently have a prototype multiwell assay system demonstrated on cancer cell mechanics. Our next steps are to move from a 16 well prototype to a 96 well assay, and to validate our system on cell lines and on ex-vivo tumor cells. Our development of high throughput force assays will be applied to relate tumorigenicity to the regulated expression of TGF-2 superfamily receptors and subsequent TGF-2 superfamily signaling. TGF-2 and the related TGF-2 superfamily ligands, the bone morphogenetic proteins (BMPs) and inhibin, are potent regulators of normal epithelial cell proliferation, differentiation, survival and migration, with frequent disruption in these homeostatic mechanisms resulting in human cancers and driving human cancer progression, including the metastatic process. We will assess dynamic changes in biomechanical properties during epithelial- mesenchymal transition (EMT), and investigate the migratory, invasive and metastatic potential of these cell models both in vitro (cell lines) and ex vivo and correlate these results with the biomechanical measurements. These measurements will validate our high throughput force system for a wide variety of cancer cell biology studies, enabling the elucidation of the biochemical and genetic determinants of metastatic behavior.